System of control



, NOV. 1929- E. M. BOUTON 1,034,198

sirsmn OF CONTROL Filed Oct; 14; 1924 ATT'ORNEY WI NESSE: I INVENE'OR Af'qyar/li Boa/0n 15 the appended claims.

determined this means, the

as... Nov. 5, 1929 UNITED STATES PATENT 'orrics EDGAR I. BOUTON, OF EASTPITTSBI IRGH, PENNSYLVANIA, ASSIGNOR 'TO WESTI ING HOUSE ELECTRIC dcMANUFACTURING COMPANY, A COBYORATION O1" PENNSYIz-f VANIA srs'rm orcommon A ppncaticn filed October '14, 1924. 'Serial n. 743,512.

My invention relates to systems of control and it has particularrelation to such. syss tems as are employed in connection withelevators,hoists and -similar machines.

5 An object of my invention is to improve .the operation of a variablevoltage control system so as to eliminate shocks, occasioned byunskillful handling.

Another object of my invention is to pro vide an improved control forthe electromag netic braking mechanism.

Other objects of my invention will be made apparent by the followingspecification and My invention will be described in connection with theaccompanying drawing in which the single figure is a diagrammaticrepresentation of circuits and apparatus embodying my invention.

With reference to the accompanying drawing, a motor having an armature 1is connected in a loop c1rcu1t'w1th a; generator also having an armature2. Separately excited;

i field-magnet windings 3 and 4 are provided for the motor andgenerator, respectively. Suitable excitation for the field-magnetwindings and for the operation of various control devices is erator.During normal operation thewind- 'ing 7 is conne'at'atedto form a closedcircuit in order. that it may act as a damper-windrevent. too rapidchanges in field flux of t e generator.

- A suitable electromagnetic brake 8,having an operating coil 9, isprovided tor contro lin the motor armature in a famihar manner.

45 A rake discharge resistor 11 is connected-in arallel relation to thecoil 9, and a-relay 12, aving an operating c011; 13,*1s connected toshunt a portion of resistor 11 when the gen- ;erator field-winding d isenergized to. a m

rovided by 'means of an exciter 5 which is 'rectly connected to thearmature tin of the brake may be controlled as herema er set forth.Reversing means comprising switches 14: to 17, inclusive, is providedfor the field 4. The switches 14; to l 17 together with a brake switch'18, may be controlled bymeans of a master switch in the customarymanner.

The generator field ex-' citation may be controlled by means'of anadjustable resistor 19. An inductance device 20 is also connected incircuit with the field winding 4. A speed relay 21'is connect- 1 ed forcontrolling a portion of field resistor 19. The relay 21 is controlledby masterswitch contact members 22. A discharge res stor 23 19 providedfor the field winding 44" and is controlled by means of a relay 24 thatis also under control of the master-switch d contact members 22.

M invention will be best magma from A 7 the ill llowing description ofoperation. Assumrng the apparatus to be in its illustrated and inactivecondition, the motor l'is started by the closure of reversing switches14 and 16' and a simultaneous closure of brake relay 18. The generatornow'operates with mini- .mum field excitation and with resistors 19 inseries and. 23 in arallel relation respec tively therewith. 1s connectedin a closedcircuit by a relay 25 whlch 1s controlled by a manuallyoperable e extra field 7 switchv26. The winding 7, therefor facts onlyas a damper-winding during normalexcitation of the generator to assistin overcoming the effect of too rapid variationin field current.,Manuallyoperable switch'22 is next closed to ener relays 24 and 21,whereby resistor 23 is disconnected and a portion of resistor 19 isshunted. The efiect of such operation, under ordinary circumstances, isto permit a sudden increase in generator field current. In this" case,however,

the rate of change of the flow" of current is limited by means of theinductance device 20, thereb preventing a too abrupt strengthcning of te generator field and havinga corresponding effect the motor.

95 upon the accelerationoi i Whereas the use of inductance A in seriesrelation wifli'the-field-win d creases the timt'by to in-- ductance ofthe field, under other conditions it may be desirable to permit thefield flux to increase more rapidly. By connecting an adjustableinductance 30 in parallel relation to the field-winding 4-, the rate atwhich the winding becomes fully energized may be'increased above thenormal or inherent rate due to. its own inductance. In other words, aninductance connected in parallel relation to a winding tends to decreasethe inductive effect of said winding, whereas, a series-connectedinductance adds to the inductive efl'ect of said winding.

Deceleration of the motor is effected upon the opening of switch 22,whereupon relay 2 immediately connects resistor 23 in par allel relationto the generator field-winding 4. Relay 21 does not open simultaneouslywith the closure of relay 24L for the reason that I have provided anadjustable inductance device 27 and a suitable resistor 28 in circuitwith the operating coil of relay 21. The time element of relay 21 maybe, in this manner, adjusted over a considerable range of operation, asmay be required to prevent a too sudden reduction in the generator fieldexcitation.

It may be noted that relay 12 is arranged to close during theacceleratingperiod and to remain closed as long as the excitation of thegenerator windin t exceeds a predeter mined value. Thereibre, during theperiod of deceleration, relay 12 remains closed and, when the brakerelay 18 is opened, the counter E. M. F. of the brake coil 9 dischargesthrough a portion of resistor 11. The time element of the' brake coilmay be adjusted by varying the amount of resistance in circuittherewith. This matter is of importance on account oftwo conditions ofoperation commonly encountered. When stopping from high s eed, it isdesirable to prevent the setting o the brake until deceleration has beenefiected by means of field control and dynamic braking. However, wheninchin the motor, it is necessary to rmit quic application of the.brake. This efiect is insured, in the present instance, by providingthat rela 12 will not be suflicientl energized to ie up during periodsof inc 'ng and, there ore, the entire resistor 11 is connected incircuit and is preferably of such value as to have sli ht retardingeffect upon the brake.

witches 14 and 16, when open, disconnect the separatel excitedfield-winding 4 and, simultaneous y therewith, switch 26' may be openedto de-energize relay 25 and connect the auxiliary field winding 7 incircuit with the generator armature 2. The winding 7 is connecteddifierentially with respect to winding 4 and is of such value as toovercome the residual magnetism of the generator field.

My invention provides a simple and effective variable-voltage controlsystem that embodies a minimum number of control switches. The system isof such character that a large speed range or adjustment may be effectedsmoothly and without the necessity of particular care in themanipulation of the master switch.

I have illustrated my invention in simple ator, and means for renderingthe second winding eflective as a damper-Winding throughout theaccelerating period.

2. The combination with an electric motor and a variable-voltagegenerator there for, of manually operable means for varying thegenerator voltage, means for automati cally controlling said-voltageduring deceleration of said motor andmeans controlled in accordance withthe generator excitation for regulating the braking of said motor.

3. The combination with an electric motor and a variable-voltagegenerator therefor, of manually operable means for varying the generatorexcitation, an electro-magnetic brake for said motor, and meanscontrolled in accordance with the excitation of said generator forcontrollingsaid brake.

4. The combination with an electric motor and a variable-voltagegenerator therefor, of manually operable means for varying the generatorexcitation, an electro-magnetic brake for said motor, manually operablemeans for controlling said 'brake and means for controlling the settingof said brake in accordance with the excitation of said enerator.

5. he combination with an electric motor and a variable-voltagegenerator therefor, of manually operable means for varying the generatorexcitation, an electro-magnetic brake for said motor, manually operablemeans for controlling said brake and a relay having a coil in circuitwith a field winding of said generator for delaying the setting of saidbrake.

6. In a control system, a motor, a gener-w ator for supplying voltage tosaid motor, means for varyin the voltage generated for varying the specof said motor, means including a demagnetizing field winding for saidgenerator, normally connected in a closed circuit to govern the rate ofchange of said voltage, and means for automatically connecting saidwinding across the armature of said generator when said generator isoperated to stop said motor.

7. In a motor-control system, a motor, a generator for supplying voltagethereto com prising an armature,a separately excited field winding,means for controlling the excitation of said winding to control thespeed of said motor, an additional field Winding, and means'forconnecting said additional field winding in a closed circuit while saidmotor is operating to govern the rate of change of speed of said motoreffected by said excitation controlling means and for connecting saidadditional field Winding to said generator armature when said motor isto be stopped to act as a dynamic brake.

8. In a motor-control system, a motor, a (generator for supplyingvoltage thereto, said generator including an armature, a sepai'atelyexcited field winding and an additional field winding, means forcontrolling the excitationof said separately-excited field winding forvarying the voltage supplied by said generator to said motor to startand stop said motor, means for connecting said additional field windingin a closed circuit to govern the rate of change of voltage under theinfluence of said excitation-controlling means and means operable inresponse to actuation of said excitation-controllin g means to stop saidmotor for connecting said addie tional field Winding across saidgenerator armature.

- In testimony whereof, I have hereunto subscribed my name thisfirst dayof October,

EDGAR M. BOUTON.

